Compressor Frequency Control to Reduce Protective Restart Cycles
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Solution Overview
Problem
Air conditioners experience frequent compressor restarts when operating in heating mode with high outdoor temperatures or cooling mode with low outdoor temperatures, leading to protective shutdowns and inefficiencies.
Innovation Solution
A method and device that adjust the compressor frequency and operation duration based on the number of protective stops, lowering the frequency and duration when restarts exceed a preset threshold to prevent overheating or overcooling, and restore settings when conditions improve, with adjustments for refrigerant leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compressor operates at preset frequency (60 or 90 Hz) for over 1 minute after startup, then the compressor needs to reach stable operating conditions, but the evaporator temperature reaches protective values quickly causing frequent restarts every 5 to 7 minutes
Solution Approach 1:
The patent applies dynamics by making the compressor frequency adjustable rather than fixed. The control method dynamically changes the compressor frequency from initial high frequencies (60-90 Hz) to lower frequencies based on operating conditions, allowing the system to adapt to prevent evaporator temperature from reaching protective values while maintaining stable operation.
Solution Approach 2:
The patent changes the frequency parameter of the compressor based on the number of protective stops. When protective stops exceed a first preset number, the frequency is lowered; when protective stops exceed a second preset number, the frequency is restored to preset values. This parameter adjustment prevents frequent restarts by avoiding evaporator temperature extremes.
2Reliability
If the compressor frequency is lowered to prevent evaporator temperature from reaching protective values, then frequent restarts are reduced, but the cooling or heating efficiency decreases
Solution Approach 1:
The patent implements periodic action through staged frequency adjustment. Instead of continuously lowering frequency, the system periodically adjusts frequency based on protective stop counts: lowering when stops exceed first preset number, and restoring when stops exceed second preset number. This periodic adjustment maintains reliability while minimizing energy efficiency loss.
Data Source
AI summary
A method of controlling a compressor is disclosed. The method includes: after the compressor is stopped for protection, updating the number of protective stops of the compressor occurring during a current operation of the air conditioner; and when the number of protective stops of the compressor is greater than a first preset number, lowering the frequency of the compressor so that when the compressor restarts the compressor would start and operate at the lowered frequency. Disclosed also is a device for controlling a compressor. Thus, by lowering the frequency of the compressor, the compressor would reach the high or low temperature protective value comparatively slowly, so the number of restarts of the compressor can be reduced.